Fflachlsfe



v L. POLINKOWSKY.

MACHINE TELEPHONE SYSTEM.

APPLICATION FILED MAR. 5, 1914.

Patented Aug. 1, 1916. 9 SHEETS-SHEET l- L. POL|NKOW'SK Y. MACHI NE TELEPHONE SYSTEM.

APPLICATION FILED MAR. 5. I914. I

Patented Aug. 1, 1916.

9 SHEETS-SHEET 3 y W I M Z WM w vJu WIT/1055a L. POLINKOWSKY.

MACHINE TELEPHONE SYSTEM.

APPLICATION FILED mm 5. 1914.

Patented Aug. 1, 1916.

9 SHEETS-SHEET 4.

L. POUNKOWSKY.

MACHINE TELEPHONE SYSTEM. APPLICATION FILED MAR. 5, I914- 1,1 9.,% 3., Patented Aug. 1, 1916.

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L. POLINKOWSKYK MACHINE TELEPHONE SYSTEM. APPLICATION man MAR. s, 1914.

Patented Aug. 1, 1916.

9 SHEETS-SHEET 6.

W/irvesses:

,Wa, am

L. POUNKOWSKY.

MACHINE TELEPHONE SYSTEM.

APPLICATION FILED WAR-5.1914.

L. POLINKOWSKY.

E MACHINE TELEPHONE SYSTEM. L1 9 U53,

APPLICATION FILED MAR- 5, 1914.

Patented Aug. 1, 1916.

9 SHEETS-SHEET 8.

L. POLINKOWSKY.

MACHINE TELEPHONE SYSTEM.

APPLIC'AIIO'N FILED MAR. 5. 1914.

1,, 1 9,U5 3 Patented Aug. 1, 1916.

9 SHEETS-SHEET 9.

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- 1 fla/f/z/mm//ry LIPA POLIN KO'iJV SKY, OF BRUSSELS, BELGIUM, ASSIG-NOR, BY

narcissist enrich.

Mnsnn assrenttnnrs, r0

MAGHINE TELEPHONE SYSTEM;

nan- AM Specification of Letters Patent.

Lioness.

Patented drug. ii, ilfilltl.

Application filed March 5, 1914. Serial No. 822,590.

To all whom it may concern:

Be it known that I, Lira POLINKOWSKY, a subject of the Emperor of Russia, residing at Brussels, in the Kingdom of Belgium, have invented a certain new anduseful Tmprovement .in Machine Telephone Systems, of which the following is a full, clear, concise, and exact description. I

This invention relates to machine telephone switching systems and moreparticw larly to a system of metering for use in such systems.

It is an object of the present invention to provide a metering system in which the operation or non-operation of a meter is automatically controlled independently of any operator or attendant at the exchange. In accordance with this object a metering device and circuit arrangements therefor are provided so that a meter individual to a subscribers line is controlled by means of differentially operating devices to cause the registration of a charge if a desired connec tion to a called line from a" calling line with which such meter is associated has been successful and to prevent the operation of such meter if such connection has been unsuccessful.

For the purpose of clearly disclosing the operation of the metering system of the invention such system is shown and described as applied to a complete machine telephone system, which machine telephone system containsseveral novel features which do not form; a part of this invention and are not claimed" herein. The particular devices and circuits,therefore, by which this is accom-. plished will be more fully disclosed and understood from the following description taken in connection with the accompanying drawings in which 'lF'gures-l and'l show circuits and apparatus of a subscribers line and a first line finder adapted to extend the connection of such line when calling. Figs. 2 and 2" illustrate diagrammatically the second. line finder and the connecting circuit associated'thermwith, together with the group selector. Figs.

3 and 3 illustrate the circuits and apparatus of the final selector.

ing and controlling equipment adaptedto be associated with the connecting circuit shown in 2. to control the group selector and final selector shown. Fig. 5 is a detail view Figs. 4 and 4 illus-,

I p of corresponding to the spacing plate. trate a circuit and apparatus of the register of a portion of the final selector. Figs. 1, 1,2, 2 3, 3, 4c and i taken together illustrate-diagrammatically a system involving the invention.

The figures should be arranged as follows :from left to right, Figs. 1, 1 2, 2, 3 and 3*, and Fig. 4 should be placed under Fig. 2 and Fig. 4* under Fig. 2

The line finders, group selectors and se-v quence orsteering switches are of types al ready known in the art and need not herein be specifically described, it being sufficient to describe their relation with the circuits.

'Also the method of showing the sequence switch contacts and the indication of the operating positions of the sequence switch is well understood, and mention needonly be made that in Fig. 2 the sequence switch contacts of'thethree sequence switches shown thereon are associated with the sequence switch indicated in that portion of the figure separated from the remaining portions by dotted lines. V

The mechanical construction of the registers of the registering and controlling equipment, it is thought, will be sufliciently understood from the diagrammatic showing thereof and the description of their operationl "The final selector switch differs from the final selector switches of this type previously known'only by the addition of two extra notches in the interrupter plate of the top thereof, between the first l0 notches thereof and the second 10 notches thereof. It will and the contacts of these lines are arranged in ten levels ofltwenty lines each. Between the bank of the one hundred lines individual to onehundred, and the bank of lines individual to another hundred, that is to say,

be recalled'that selector switches of this type have'a capacity of two'hundred lines,

between the first ten lines of each level and the second ten lines of each level there is a spacing plate. lin selector switches of this type previously known the spacing between the two banks of'line contacts was without effect, as the interrupter plate at the top of the selector was uncut over the portion thezien the final selector switches as used herein, however, there are two notches out in the portion of the interrupter plate corresponding to the spacing plate for purposesherein describe-d That is to say, in selecting a line .of times corresponding to the number of lines passed over plus two. This will be readilyunderstood froman examination of Fig. in which the notches a represent the notches of such interrupter plate corresponding to the first set of ten lines on the given level of the selector; the notches I) represent the notches in. such plate corresponding to the second set of ten lines on such level, and the two notches 0 represent the two extra or additional notches which have been added as above indicated for purposes hereinafter described.

The invention as disclosed herein Wlll be 1 best understood from a description of the operation of the system shown.

Assuming that the subscriber at the substation indicated at 120 desires connection with the subscriber indicated at 320, whose .number is 307, he first removes his receiver from its switchhook, thereby closing a circuit for the line relay 121, which on its energization closes a circuit for and energizes the pilot relay 122 common to a group of incoming lines which appear multipled upon a given group of first line finders such as the one shown in Fig. 1. Relay 122 closes a circuit over the sequence switch springs 104 and 103 for the power magnet 123 of all the first line finders of this group which are at this time in idle condition; that is, whose sequence switches 100 are in first or normal position. Such idle line finders will, therefore, start in motion, moving their -brushes 125, 126, 127, '128 over the terminals 129,

I 130, 131, 132 of the lines appearing in such line finders, and testing such lines in the usual way. As one of them, however, brin'gs its brushes into contact with the terminals of thecalling line, it will find upon the terminal 132 of such line'a selectablepotential, produced by the energization of the line 1 terminal 132 that such line is relay 121 and determined by the resistances 133 and 134. Immediately that the brush 128 comes in contact with the terminal 132 upon which such selectable potential exists, the test relay 135 will be energized over the springs 102 bottom, 108 top and'either the spring 106 or the interrupter brush 136. The energization of this relay 135 closes through its armature a circuit through its low resistance. holding winding for itself the closure of such circuit through such winding so reducing the potential upon the no longer selectable, and any other line finder whose brush 128 comes in contact with such terminal 132 will not be stopped. The carriage of the line finder which has thus seized the relay 137 has also driven the sequence switch 100 out of its first into its second position. In this movement of the sequence switch a test guard is maintained upon the terminal 132 and the seized line through the spring 112 bottom, the spring 102 bottom being opened as the sequence switch leaves its first position. In the second position the spring 110 being closed, the cut-off relay 139 of the calling line is energized, causing the deenergization of the line relay 121 and the consequent deenergization of the pilot relay 122, provided no other line of this group is at this time calling and not as yet been seized by a line finder.

The meter 55 individual to the line is connected as shown in parallel with the cut-off relay 139 also individual to such line. However sufiicient current will flow over the circuit just traced to cause the energization of cut-ofi' relay 139, but suflicient current will not flow over this circuit to cause the energization of the meter magnet. The deenergization of the relay 121 opens the battery circuit to the terminals 132, and the line now having been seized and being maintained busy, no selectable potential is possible upon its test terminal 132.

The sequence switch 100, 011 coming into its second position, has established a circuit over spring 113, the pilot wire, and the springs 602 bottom, back contact of relay 237 and spring 603 top for the power magnets 226 of the idle second line finders in which the circuit connected to the first line finder shown appears in multiple. brush carriages of such idle line finders, therefore, move the brushes 227, 228, 229, 230 over the'contacts 231, 232, 233, 234 of the various vlines appearing in such line finders. The sequence switch 100, on coming into its second position, by closing the springs 108 bottom, 106 top and 107, has placed selectable potential on the terminal 234 of the trunk-line or circuit connected to the first line finder associated with such sequence switch 100. \Vhen the brush 230 of one of such second line finders comes in contact with the terminal 23 1, upon which this selectable potential exists, thetest relay 235 will be energized, the circuit for such relay including the springs 604 top, 605 top and either the interrupter brush 236 or the spring606 'top. Such relay 235 will there- The intense fore, be energized, closing in parallel to its righthandwinding a circuit including the low resistance holding winding, which will so reduce the potential upon the terminal 23 1 that no other second line finder can now interrupter brush is opened, and, the shunt being thereby removed from around the power-control test relay 237, such relay is energized to stop the switch in the usual manner by opening the circuit of the power magnet 226 and closing the circuit of the holding magnet 288, at the same time driving the sequene' switch 600 out of its-first into its second position by closing a circuit over the spring 607 top.

As the sequence switch 600 leaves it s-first position, and until it has passed through its seventh position, a busy test guard is maintained upon the terminal 234 by the closure of the spring 610, connecting ground to such terminal. y

As the sequence switch 600 was passing from its first into its second position, the spring 611 was closed. sufficiently long to drive the sequence switch 200 out of its first position, the circuit for moving such sequence switch including the spring 202 bottom. This sequence switch comes to rest in its second position.

In position 2 of the sequence switch 600, and in position 2 of the sequence switch 200, the selection of an idle registering and controlling mechanism will take place. Before considering this operation, however, the various effects of the seizure of the circuit connected to the first line finder, and the movement of the sequence switch 200 into position 2 will be considered. When the test relay 235 was energized, the circuit therefor also included the relay 137, to maintain it energized, and relay 137 being energized the sequence switch 100 is moved from its second position to its fifth position.

In position 5 the circuit for relay 137 will include the resistance 140 as well as the resistance 141, but such relay will be maintained energized so long as the spring 610 top is closed. 1n position 5 of the sequence switch 100,

the spring 110 being open, the circuit for the cut-ofi' relay 139 now includes the spring 102, the relay 135 and the spring 207, the sequence switch 200 now being in the second position. lnthis position also the sprlng 112 is open andthe circuit of the calling line is extended over the springs 210 top and 211 top to the repeatingcoil 239. a

As' the sequenee switch 600 came into its second position, the springs 604 bottom, 6.19

ttlll 005 bottom, fi tlfibottom and 613 bottom were closed. If at this time the sequence sw tch 700 individual to the connecting circu1t shown is in such position that an idle registering and controlling equipment is con- 700 is already busy, the test circuit including the relay 240 of some other connecting circuit will already be energized over the circuit including the relay 126 and insuiiicient current willpass through the relay 240 shown, to energize it. A circuit will, therefore, be established over the back contact of such relay 240 spring 613 bottom and spring 702 to cause the sequence switch 700 to move and it will continue in motion until on closing the circuit from the leads of the connecting circuit to the leads of an idle equipment the relay 240 is energized, at which time the circuit over the sequence switch 700 will be opened and the relay 237 being energized in parallel with the relay 2 1 0 the sequence switch 600 will be driven through sequence switch springs 602 top and 607 top from its second into itsthird position. In this position the relay 240 and the relay 237 are directly connected over the spring 619 bottom and over the spring 704 bottom, for example as shown, to the starting relay t26. This idle registering and controlling equipment is now seized and is istering and controlling equipment is now complete, such circuit being traceable from battery through the stepping relay 427, spring 402 of the sequence switch 400, spring bottom of the sequence switch 700, spring 210 bottom of the sequence switch 200, brush 228 and terminal 232 of the second line finder switch, brush 126 and terminal 130 of the first line finder switch over the subscribers line and through his substation, terminal 129 and brush of the first line finder switch, terminal 231 and brush 227 of the second line finder switch, spring 211 bottom, to

ground and back to battery.

The relay 4-26 being energized, asbefore described the sequence switch 400 is driven 'ries comprising three impulses.

tus will now await the sending of impulses by thecalling subscriber, such impulses belng arranged in groups correspondlng to the complement of the digits of the numerical designation of the called subscribers station-that is to say, the called subscribers number being assumedto be 307, the calling subscriber will transmit to the central station. three series of impulses, the first series comprising seven impulses, the second series comprising ten impulses, and the third se- In each of these series of impulses the last impulse sent will be relatively longer than the other impulses of the series, which other impulses are in fact quite short. The sender by which these impulses are sent may be of any desired structural character, provided that the impulses are sent in a complementary manner, and that the last of each of the groups of impulses sent by such device is relatively longer than the other impulses of such group. A sender is diagrammatically shown capable of accomplishing the necessary functions, and in which the settingof the sender produces no impulse in the circuit. The impulses as produced in the system as disclosed are interruptions of the circuit.

The system herein disclosed is for clearness shown only as a 1000 line system. In such a system there will be five groups of final selectors, each accessible to 200 lines thereof, and the group selectors used will Y have only five of the ten banks thereof utilized, one bank of contacts being connected to the trunk lines of the group of final selectors individual to one group of 200 lines, another connected to another group of final selectors individual to another 200 lines, and so on. In accordance with the translating system disclosed herein, the selection in the group selector of the trunk line leading to the group of lines having the proper hundreds digit is such that if the, 100s digit of the desired line is zero or one, the tripping spindle of the group selector Will be adjusted to release the proper set of brushes on the brush carriage by the movement of such spindle one step or stage. If the 100s digit of the desired line is two or three, such spindle will be moved three steps or stages. If the 100s digit is four or five, the spindle will be moved five steps or stages. If the 100s digitis six 0* seven, such spindle will bemoved seven steps or stages, and finally it the 100s digit is eight or nine, such spindle willbe moved nine steps or stages;- Of I course, it will be understood that if the system is for more than 1000 lines, the interme diate steps or stages, that is, second, fourth, sixth, eighth and tenth will be reserved for use when a trunk line is desired leading to the groups of selectors having access to the lines of such second thousand. In a 1000 line system as herein disclosed, the trunk lines may be, and it will be assumed are, connected to the alternate levels of contacts in such group. selector. It will be further understood that by properly rearranging the tripping teeth upon the tripping spindle, the five levels and terminals which are used may be arranged, if desired, adjacently to each other, so that the first level will be selected by a single step of the tripping spindle, the second level by three steps of such spindle, the third level by five steps of such spindle, and so on. Furthermore, if preferred the arrangement of the lines of the subscribers upon the final selectors may be so arranged that the trunk line leading to a corresponding group oi 100 in each of the two thousand lines accessible through a group selector will be selected in the same level of such group selector, such arrangement resulting in'the selection of a line whose 100s digit is zero in either thousand by one step of the tripping spindle of the group selector, a line whose 100s digit is 1 by two steps of the tripping spindle, and so on. As shown, however, the arrangement of the lines and the selection in the group selector will take place as first above described.

An operation, therefore, of the subscrib ers sending mechanism to send the 100s digit 3 will produce seven breaks in the circuit hereinbei'ore described, including the stepping relay 427, the last of such breaks being relatively longer than the others of the group. Upon the initial encrgization of the stepping relay 127 a circuit was closed by its armature over the spring 108 and the back contact of the changeover relay 428, including the lower winding of the 100s register 4:29. This causes the energization of the power magnet of such register and it moves until when midway between its zero or norn' a1 position and its first position, its local positioning or A spring an is closed.- At this time a circuit is closed over the front contact of the relay 426 and such. positioning spring through the upper winding of this register. The two windings of the register are difierentially wound on the power magnet thereof, so that when a circuit is'closed through both of said windings, or when there is a circuit through neither of said windings, such register will stop; whereas, when a circuit is closed through butone of said windings the register will move. The register 429, having therefore been broughtsto rest between its zero and first positions, will await the opening of the over the spring 458 bottom will drive such. -register one additional position, that is in this case into its eighth position. Also as the sequence switch 450 passes through its third position the translating relay 432'be ing locked up a circuit will be established.

over the spring 460 top, left-hand armature of such relay and spring 461 bottom, to drive the 100s register 429 from its eighth into its ninth position.

On coming into its fourth position the sequence switch 600 being already in its third position, the fundamental circuit from the registering and'controlling equipment is closed to the group selector shown on Fig. 2. This circuit includes the line relay 242 of the group selector, and the selection controlling stepping relay 433 of said equipment, both of which relays will be energized. This circuit also includes the springs 612, 473, 457 and 611 bottom. The energization of the relay 242 drives the sequence switch 600 into its fourth position over the spring 614, in which position the circuit for the tripping spindle power magnet 243 is closed and the tripping spindle starts in motion. In moving from position 3 to 'position4, sequence switch 600 makes no changes in the fundamental circuit.

As the relay 433 was energized coincidently with the energization of the line relay 242,it closed the circuit over the spring 458 top for the lower winding of the 100s register 429; the register, therefore, moved a half of a position, that is until the closure of the circuit through its upper winding and the positioning spring 471 thereof is closed. As the tripping spindle of the group selector began to move it intermittently closed a circuit to ground, such circuit being so con-' nected to the-fundamental circuit that when.

it is closed the relay 433 will be shunted and deenergized, though the line relay 242 is energized. This deenergization of the relay 433 will take place once for each movement of the tripping spindle one step or stage. Upon which position it will be moved to a position intermediate between the group selector, in the continued motion of the tripping spindle a second deenergiza- 'tion of the relay433 takes place and the 1 0( )s register is moved into its sitlon, to be moved again into a termediate between its eleventh eleventh poand zero p.0

three steps or stages, release the third set'of brushes-on the brush the deen'ergization of i the relay 433 the 100s register again. moves until it comes into its tenth position, from l the back contact its tenth and eleventh movement,

position insitions, when the shunt is again removed at the tripping spindle.

The next closure of the earth connection at the tripping spindle, and the consequent third deenergization of the relay 433 drives the 100s register into its zero or normal position. In this position the spring 473 is open and consequently not only will the relay 433- remain deenergized when the connection to earth is broken at the tripping spindle, but also the line relay 242 will be denergized, both the fundamental. circuit and the branch circuit to ground being now open; ,As soon as this occurs, the circuit for the tripping spindle power magnet 243 is open at the front contact of the line relay 242, and the tripping spindle is brought to rest. Such tripping spindle, having moved is now in position to carriage of the group selector, as it will be recalled, that a trunk line leading to the group of finalselectors in which the desiredline appears is to be'found in the third bank orlevel of such group selector.

As the 100s register came into its zero or normal position, if the incoming sequence switch 400 is in its ninth position-that is, if tens and units registration is ,complete a circuit will be closed including the springs 456, 472 and 410 to drive the outgoing sequence switch 450 into its sixthposition, in which it is ready to control tens selection as soon as an idle trunkline to a properfinal selector has been found and seized in the group, selector, as will be described. If

' the incoming sequence switch 400 is not as yet in its ninth position, the outgoing sequence switch 450 will remain in its fourth position, moving into its sixth' position as soon as the sequence switch. 400 reaches its ninth position. v

When the line relay 24-2 stopped the movement of the tripping spindle. of the group selector, it also closed acircuit over its back contact and the spring 602 top, back contact and armature of the relay 237, which is deenergized after the sequence switch 600 left its third position, and spring 607 bottom, to drive the sequence switch 600 into its fifth position.

In the fifth position a circuit will be es tablished for the group selector power magnet 244, including the spring 603botto1n' and armature of relay 237, sequence switch spring 602 top and contact and armature of the line relay 242.

-The brush carriage of the group selector,

therefore, will begin to move in its first brushes to be released in the movement past the said tripping spindle and then causing such released brushes 245, 246 and 247 to make contact with the various sets of concausing the proper set of lib the back tracts inthe selected level. So long as the 1'80 test brush 2&7 makes contact with the'testf terminals of trunk lines which are already engaged, insuficient potential will be found thereon to energize-the relay 235 due to the fact that the low resistance winding of a relay corresponding to the relay 235' of some other group selector is already connected to the terminal multipled to such test terminal.

,- brushes come in contact with a set of termi- As soon, however, as. the

nals individual to an idle trunk line, full potential will be found on the test terminal thereof, anda circuit will be established for the test relay 235 extending from battery at 'final selector over the s ring 312 bottom,

spring 31410 the left winding of the relay 331, test conductor of the seized trunk line, test brush 24:? of the group selector, right- .hand high resistance winding ofthe test Jrelay 235, spring 5605 top,= power control test relay 2.3-7 and spring 606 top to ground.

The test relay235 will be energized, butthe relay 23? will not be energized owing to the shunt 'therearound existing over the interrupter brush Theenergiz'ation of the relay 235- closes a low. resistancecircuit through its left-hand winding parallel to its right-hand winding, which so reduces the potential upon the test terminal of the trunk line that the test relay 235 of no other group I selector, the brushes of which come in contact with the terminals ofsuch line, will be energized. .hssoon as the brush carriage,

'which is continued in motion, properly centers the brushes upon the terminals of the seized line, the shunt circuit through the interrupter brush "will be open and therelay 4: 1 a H 0.1 toe s 237v will be energized. The energization of this relay will open the circuit for the power magnet 24 i and close the circuit for the holding magnet 250 over the springs 608 top and 607 top, so that the brush carriage of the group selector will be properly and accurately stoppediin the well-known manner. The energization of the relay 23 7 -l1as also In this position of thesequ'ence the closure of this circuit at. this time depends upon whether the outgoing sequence switch 4:50 has reached When the sequence switch L50; was driven out of its fourth position uponthe comple tion of the hundreds selection controlling operation, it moved directly. into itssixth position, but in passing through its fifth position the momentary closure of .the spring 4-62 bottom has driven the'tensregister into its eleventh position in the now well-understood ma oer. When new the fundamental circuit as am closed 1n the sixth position oe-nee switch r50, including the the gized. At the same time the closing of the its sixth position.

line relay 332 at thefinal selector, spring 308 top, brush246 of the group selector, spring 617 bottom, spring 483 of the lOs register, spring 453. top, relay 433, spring 616 bottom, brush 245 of the group selector, and spring 309 top to ground, the relays 332 and Q33 are both energized. The energize.- tion of the relay 332 drives the sequence switch 300 into its second position by the closure of the circuit over the spring 303 top, in which position the circuit for the tripping spindle power magnet 333 is closed over the spring 302 bottom and the front contact of the relay 332. The tripping spindle will thereupon begin to move. The energization at this time of the relay 433 has closed a circuit over thespring l62 top 'to move the tens register one-half of'a position from the position in which it was set as described.

It will be recalled that the l0s digit of the desired line is zero, and therefore such line is to be found in the first bank or level of the final selector. It will therefore be necessary that the selection controlling operation of the final selector should be terminated when the tripping spindle has moved. one

step or stage and is in position to releas'ethe set of brushes corresponding to thepfirst bank set or level of contacts. It will also be recalled that the l0s' register was set by the subscriber in its tenth position and subsequently moved to its eleventh position. When, therefore, the tripping spindle at the final selector moves its first step or stage, the. shunting of the relay 433 in the well-known manner drives the 10s register into its zero or normalposition. This movement of the l0s register; immediately opens the-fundamental circuit at the spring 483 of such register, .so that when the shunt circuit through the tripping spindle is opened both relay 133 and the relay 332 are de'e'nerspring 482 of the 10s register closed a cir- ;clnt including the springs 411, 432 and 463 -.top to-drive the outgoing sequence switch @550 into its eighth position ready to control -j'units'selection, and the fundamental circuit which has been maintained open between the sixth andeighth positions of such sequence {switch will there await its second closure at the {final selector. Immediately upon the de- "energization of the line relay 332 as just described the .movement of the trip ing spindle is stopped, itheing now inposition to trip the first set of brushes onfthe brush carriage, and the sequenee switch 300 is driven from its second position to-come to rest in its fourth position. --2ts the outgoing sequence switch 450 of the registering and controlling equipment moved through its seventh position upon the termination of tens selection the momentary closure of the spring 454 moves the units register one addipower magnet of the final selector, and such brush carriage begins to move. In the initia'l movement of the brush carriage, the

- proper set of brushes (in this case the first set) ,is tripped as the carriage passes the r tripping spindle. In the subsequent movemerit of the brush carriage the brushes 334,

335, 336 sweep over the sets of terminals individual to the lines multipled to this bank or'level of contacts. For each movement of such brushes to a set of terminals the interrupter device 337 closes a circuit to ground from the fundamental circuit over the springs 313 top and 315 in the well-known manner, such circuit to ground as is well understood shunting the relay 433 while maintaining the relay 332 energized.

Upon the energization of the relay 433 and its subsequent intermittent deenergization due to the shunting action of the contacts of the interrupter 337 at the final selector, the units register will besteppe'd in the well understood manner, one full position for each energization and subsequent deenergization of the relay,433". At the end of eight of such operations of the relay 433 the units register will again be in its normal position, the-selected brushes of the final selector at this time being about tomake contact with the eighth or No. 7 set of contacts 0f the bank or'level to which they are individual. It will be recalled, however, that since the desired line is located in an odd hundred, the particular line desired is to be found in the second half of the finalselector', and it is therefore necessary that the select ing operation-should not terminate at this time. For this reason the fundamental cir-.

f cuit is not opened at this time at the spring 493 as would be otherwise the case, a shunt being maintained about such spring, such shunt including the spring 460 bottom, lefthand armature of the translating relay 432 and the spring 461 top. It will be recalled that the relay 432 was locked up when the sequence switch 450, in passing from its first to its second position, tested the condition of the 100s register 429, and on finding it in a position corresponding to an odd hundred, completed the circuit for-the translating relay 432. The fundamental circuit not being open at this time, the brush carriage at the final selector will continue to sition.

sequence switch move until the units register 431 has made a complete revolution as a result of such movement. This means that the units register will take twelve additional steps. It will now be seen for what purpose the two additional notches in the interrupter plate of the final selector are provided, as hercinbefore described. To reach the contacts of the desired line after the units register has first reached its normal position would otherwise produce only ten deenergizations of the stepping relay 433, and consequently only'ten steps by the units register.

Since it is necessary that the units register should come into its zero or normal position in order to cause the cessation of selection, it is necessary that two additional steps be provided for and, consequently two additional notches are eut in the interrupter plates of the final selector to produce such steps. Therefore, after the stepping relay 433 has been operated twelve additional maintained momentarily by the spring 492.

The sequence switch stopped in its tenth polVhen now the units register 431 comes a second time into its normal position the shunt around the spring 493 thereof being opened at the springs 460 bottom and 461 top, the fundamental circuit is immediately opened, producing the deenergization, in the manner well understood, of the relays 332 and 433 to terminate selection in the final selector. The units register 431. coming into its normal position again closes the spring 492, and the sequence switch 450 returns to its normal position, in which movement in passing through position 11 it closes a circuit at spring 455 bottom to return the sequence switch 400 to its normal position. It should be also noted that the sequence switch 450, on leaving its ninth position, opened the locking circuit of the translating relay 432. The desired line now having-been selected, the services of the registering and controlling equipment are no longer required for this connnection, and therefore as the sequence switch 400 left its ninth position the spring 406 opened the circuit for the relays 426 and 240, which circuit had been substituted for the one originally established over the spring 405 as the 400 left its first position. The relays 426 and 240 are therefore dec'nith ergized. The energization of the relay 4:26, and the restoration of the sequence switch 400 to normal will cause the registering and controlling equipment shown on Fig. 4 to 7 test idle and accessible to any connecting circuit taken for use which has access to it. At the same time that the relay 426-is denergized the relay 240 was denergized and by the retraction of its armature closed a circuit to drive the sequence switch 600 from its sixth into its S\(:Iltl1 position. This is the through or talking position of this sequence switch. In this movement, however, the contact 611 top is closed and'the sequence switch 200 is driven from its fourth into its fifth position. In these positions the sequence switches 600 and 200 await the further operations of the final selector apparatus shown on Fig. 3.

Upon the deenergization of the relay 332 at the completion of the units selecting op-- eration, the sequence switch 300 is driven from its fourth position, and it will move to its sixth position. When the trunk line to this final selector was first seized, it will be' recalled that the seizing circuit included one of the windings of the relay 331 and the spring 314 top. This relay was therefore energized, and closed for itself a circuit to take the place of the circuit through the 4 spring 312 bottom, which is opened asthe sequence switch 300 leaves its first position. As the sequence switch moves from its fourth to its fifth position, the spring 314 top is opened and 314 bottom is closed. The relay 331 is maintained energized, both of its windings now being included in the circuit and the battery is connected over the spring 314 bottom to the power control test relay 339. At the same time the spring 307 top is closed, connecting battery with a high resistance winding of the test relay 349. The fifth position of the sequence switch 300 is the testing position thereof. It in this position full potential is found upon the test terminal 342 of the desired line, in-

dicating that the line is idle, the test relay 349 will be energized over its right hand high resistance winding. If on the other hand the normal potential upon such test terminal 342 is reduced by such line being busy, either as a calling line or a called line,

as will occur in the well-known manner, the

test relay 349 will not be energized. Assuming first that the line is idle and that such relay is consequently energized; it closes overits armature a circuit, through its low resistance left-hand winding and .the test relay 339, in parallel to its right-v hand winding, which will so reduce the potential of the test terminal of such seized line that it will test busy in all other final selectors in which it appears. Such circuit will also energize the relay 339 and when the -sequence'switch 300 comes into the sixth case the particular line selected is found busy. The apparatus for performing this operation is not shown, however, and in order to drive the-sequence switch through its sixth position, which is, as shown. an idle position, whether the desired line is found idle or busy, the spring 317 is provided.

The twelfth position of the sequence switch 300 is the ringing position. In this position ringing current is projected over the calledline by the closure of the springs 310 bottom and 311 bottom.

Asthe sequence switch 300 passed through its eighth position. the trunk line leading to its final selector was shortcircuited by the closure of the spring 309 bottom. This causes the momentary energization of the supervisory relay 2&8, which by the attrac tion of its armature drives the sequence switch 200 into its eighth position. This would cause the subscriber to receive the busy tone by the closure of the springs 212 bottom and 213 top, except for the fact that almost immediately after as the sequence switch 300 passes from its eleventh into its twelfth position, the spring 309 bottom is again closed energizing the relay Q-fSto drive thesequence switch 200 into its eleventh position. In this position of the sequence switch 200, the springs 212 top and 213 bottom being closed, the subscriber re- .ceives the distinctive ringing tone, and will continue to receive such tone so long as the sequence switch 300 remains in its twelfth position. does not respond, insufficient current will pass over the ringing relay 343 to energize So long as the called subscriber it. As soon, however, as the path for diposition, thesequence switch200 being in its fourteenth position, the sequence switch 600 being in its seventh position, and the sequence switch 300 being in its thirteenth position, the calling subscriber and the called subscriber are now connected, each sub 'scriber beingsupplied with transmitter current fromthe battery shown in connection. with the repeating coil- 230. Conversation.

may now take place.

The operation described is the normal operation in which an idle desired line is.

selected, seized and signaled, and. the sub{ scriber thereon responds. In such an 5 op.- eration it will be noted that the called supervisory relay 248 is three times energized, first to move the sequence switch 200 from I its fifth position toits eighth position;'next to move such sequence switch from its eighth position to its eleventh position; and

finally to move such sequence switch from its eleventh position into its fourteenth position. The importance of these. three operations will later appear. Disconnection a rwl mtemhrg.-Disconnection in the system shown may take place under the control of either subscriber except that if either subscriber should be slow in hanging up his receiver, or should ne'glect to hangup his receiver after the other subscriber has done so, the particular switch (first line finder in connection with the calling subscriber, and the final selector in connectionwith the called subscriber) will be.

maintained in an elf-normal condition, in order that such subscriber may not seize and tie up a connecting circuit and registering and controlling equipment by his failure to restore his receiver to its switchhook. However, the call having been successful, it is necessary that the metering operation should take place to charge a call to the calling subscriber, even in the case that both of such subscribers restored their receivers to their hooks, or whether only one of such" subscribers does so independent of whether such one subscriber is the calling subscriber quence switch 600 including the springs 203, 209 bottom, to move such sequence switch out of its seventh and into its eighteenth position. The restoration, therefore, by either of the parties of their receiver to its switchhook, causes such movement of the sequence switch 600. The movement of the sequence switch 600'out of its seventh position opens at the spring 610 the circuit of the relay 137 .at the first line finder 'which my the retraction of its armature 019595 a circuit includingthe spring 105 bottom to move the sequence switch 100 out of its fifth position and into its ninth position. The movement of the sequence switch 600 into its eighth position closes a circuit including the spring 609 bottom to drive the sequence switch 200' out of its fourteenth position and into its normal position. The sequence switches 600, 200 and 100 are therefore simultaneously moving, the sequence switch 600 having started from its seventh position, the sequence switch 100 having started from its fifth. osition, and the sequence switch .200 having started from its four-v teenth position. Therefore as the sequence switch 200 is passing through its fifteenth, sixteenth, and seventeenth positions, the sequence switch 100 during a part of this period, at least, will not as yet .havereached its eighth position, and a circuit will therefore be established from the high potential battery 298'through spring 207 bottom, re-

lay 135, spring 102 top, contact 131 individual to the calling line, and meter magnet 55 of the meter individual to such line. The increasedbattery impressed upon the circuit including the meter magnet 55 and the cutoff relay 139 by the closure of the contact 137 bottom is suflicient to cause the energization of the meter magnet 55 thereby causing the charging of a call against the calling subscriber. The remaining restoring operations of the system disclosed take place in the usual manner.

On coming into its eighteenth position the sequence switch 600 established theusual restoring circuit for the brush carriage of the group'selector; and such brush carriage moves until the brush 244 of the interrupter comes in contact with the normal segment, at whichtime circuit is closed over the spring 618 to energize the relay 237which stops the movement of the brush carriage in the usual'manner and drives the sequence switch 600 into its normal position.

As the sequence switch GOOleft its seventh position, it opened at the spring 010 top the circuit of the relay 137 at the first line finder. This relay thereupon, being deenergized, drives the sequence switch 100 from its fifth into its ninth position. In the eighth and ninth positions of this sequence switch a circuit for this relay is again established, provided the calling subscriber has not restored his receiver to its switch hook, which includes the spring 108 bottom, the spring 111, the substation circuit, and the spring .112 top. The sequence switch 100 will therefore stop in, its ninth position and remain there until the subscriber opens the circuit to direct current at his substation by replacing his receiver upon its switchhook. As soon as this occurs, the relay 137 will again be deenergized and drive the sequence switch 100 back to its first or normal posifinal selfector apparatus. will take sition by a circuit including the spring 102 top, and in the eight-her ninth position by a circuit including the resistance 199 and the spring 110. This transfer of control is-accomplished before the circuit of the" cutoff relay 139 was opened at the spring 207.

As the sequence switch 600 left its seventh position, it opened at the springs 605 top and 306 top the circuit for the relay 331- at the linal selector. This relay therefore imniediatcly allowed its armatures to retract, its left-hand armature closing a circuit over the spring 308 bottom to energize the line relay The energization of this relay (lri es the sequence switch 300 out of its thirteenth position into its sixteenth positiou. ()n coming into its sixteenth posi tion, the circuit at the called subscril'ier s sul ion being already opened, the relay 335? is without current and therefore is deoner ized, driving the sequence switch 300 into its eighteenth position. In this position of the sequence switch 300 the usual circuits are established to restore the switch carriage of the final selector to normal. When, however, the brush of the interrupter 33? comes in contact with ment, circuit is again established to energize the relay which, by the attraction of its annature, drives the sequence switch into its normal position. The entire paratus is now in its normal position. It will be observed, however, that although the relay 331 at the final selector is deiiner: immediately that the sequence switch 600 leaves its seventh position, it is not. again energized by the closure of the spring 610 bottom, such relay 331 controls through its right-hand armature the energi. ing current for itself in all positions, except position 1, of the sequence switch 300. However, in positions 8 to 1'7 a test guard is maintained on the terminal of the trunk line by the closure of the spring 610 bot-- tom. At the final selector, however, when the sequence switch 300 comes into its fifteenth and sixteenth positions the called subscriber not as yet having restored his receiver to its switchhoolc, a circuit will be established for the relay 332, including the springs 308 top, 310 top, subscribers line, 311 top and 309 top. Therefore, when the sequence switch 300 comes into its sixteenth position it will there stop and await the restoration of the called subscribers receiver to its switchbook, which when it occurs, will open the circuit to the relay 332, allowing suclr relay to denergize, to drive the sequence switch 300 out of its sixteenth j'iositiomaftcr which the restoration of the place as hasbeen hereinbefore described.

Attempted connection to a busy Zl 7'l/6. If

line -tential will exist upon the test terminal 342 the normal segit a.

after the final. selector switch has been moved to bring its brushes 334, 335, 336 into contact with the terminals of the desired line, and the sequence switch 300 is moving through its fifth and sixth positions, such should be found busy, insufficient poto accomplish the energization of the relay 349, consequently, no energization of the relay 339 will take place and when the sequence switch 300 comes into its tenth position it will stop, and the restoration of the brush carriage of the selector will take place over a circuit including the armature and back contact of the relay 332, armature and back contact of the relay 339, and spring 306 bottom. It will be obvious, therefore, that as a result of the fact that the desired lineis busy, but a single closure of the spring 309 has taken place, such closure being the one which takes place as the sequence switch 300 passes through its eighth position. This has resulted in but a single energization of the called supervisory relay 24.8, and the sequence switch 200 therefore stands in its eighth position, the busy tone being connected for a prolonged period across the connecting circuit by the closure of the springs 212 bottom and 213 top. The calling subscriber hearing thecharacteristic busy tone maintained on his line, will know that the line desired by him is busy, andinitiates restoration by replacing his receiver upon its switchhook. It will be recalled that at this time the sequence switch is in its fifth position, the sequence switch 200 is in its eighth position, and the sequence switch (500 is in its seventh position. The restoration of the calling subscribers receiver to its switchhook causes the de'cnergization of the calling supervisory relay Q ll, which thereby completes a circuit including the spring 252 and the spring 209 top for the sequence switch 5200. Almost immediately that the sequence switch 200 begins to move as aresult of the closureof the circuit referred to, the spring 209 top is opened, and the spring 209 bottom is closed, so that a circuit caused by. the denergization of the calling supervisory relay 2-H now exists for the sequence switch 000 which moves from itsseventh position. Restoration now takes place in the first line finder and its associated parts, the second line finder connecting circuit, the group selector and its associated parts precisely as in the normal connection the sequence switches 100, 200, and 600 "being simultaneously in motion, but it should be noted that these sequence switches have started from differ ent relative positions from the positions in which theystarted in motion in a normal restoration-that is to say, while the sequence switch 100 has started as before from.

its fifth position and the sequence switch 

